Circuit breaker control system



y 19, 1949- c. M. WILLIAMS ETAL 2,476,938

CIRCUIT BREAKER CONTROL SYSTEM Filed Nov. 28, 1945 Loo-d WITNESSES: INVENTORS c Ga'FrO/I/W. MY/fams and n/am/n [flay/a rd Q/ZJ Patented July 19, 1949 CIRCUIT BREAKER CONTRQL SYSTEM Carroll M. Williams and Benjamin 1. Hayford,

Pittsburgh, Pa.,

assignors to W estinghouae Electric Corporation, East Pittsburgh, Pa a corporation of Pennsylvania Application November 28, 1945, Serial No. 831,393

6 Claims. (Cl. 175-294) Our invention relates, generally, to control systems, and it has reference, in particular, to circuit breaker control systems.

Generally stated, it is an object of our invention to provide a circuit breaker control system that is simple and inexpensive to manufacture and is ei'ilcient and reliable in operation.

More specifically, it is an object of our invention to provide for preventing too rapid a reclosure of a circuit interrupter of the air-break type.

It is also an object of our invention to provide for timing the reclosure of circuit breakers from the time of opening. Another object of our invention is to provide a safe and reliable operating system for circuit breakers which is particularly useful with circuit breakers oi the air-break type.

Yet another object of our invention is to provide for maximum eiiiciency in the operation of circuit breakers of different types, and particularly of the air-break type.

Still another object of our invention is to provide for as rapid operation of circuit breakers which require a predetermined time for deionization as is consistent with safe operation.

It is also an important object of our invention to provide for presetting a time delay device which controls reclosure of a circuit breaker before the circuit breaker is closed, so as to provide continuity of the operating cyclic.

Other objects willin part be obvious, and will in part be explained hereinafter.

In accordance with one embodiment of our invention, an air-break circuit breaker of the mechanically trip-free type is provided with a closing relay energized through a suitable control switch and a cut-off relay of the usual type. A time delay relay is provided having an operating winding which is energized upon operation of the closing relay, and an opposing neutralizing winding which delays the return of the relay to the inoperative position. A holding circuit is provided .for the operating winding through auxiliary contact of the trip-free circuit breaker mechanism, so that a time delay period is provided for a predetermined interval subsequent to opening of the circuit breaker, within which interval the circuit breaker may not be reclosed.

For a complete understanding of the nature and scope of our invention, reference ma be 2 made to the following detailed description which may be studied in connection with the accompanying drawing. in which:

Figure 1 is a diagrammatic view of a control system embodying the invention in one of its forms; and

Fig. 2 is a diagrammatic view of a control System embodying the invention in'another of its forms.

Referring to Fig. 1, the reference numeral It may denote, generally. a control system for a circuit breaker II, which may be provided for connecting a load device It to a source of electrical energy represented by the conductors it.

The circuit breaker I! may be of the air-break type having main contacts II which operate in air to disconnect the load device it from the conductors It. The circuit breaker I! may be provided with an operating winding II for actuating an operating rod it. The contacts it may be operatively connected to the operating rod I! by a lever 20 which may be pivotally connected to a contact rod 2! and operatively connected to the operating rod It by means of dogs 22 and 2!. A latch H is provided for interfering with a projection 25 on the lever 20 to hold the circuit breaker closed. The circuit breaker may be tripped by means of a trip winding 2! which may be energized through means such as the push button switch 21 for actuating a trip rod 2| to eifect disengagement of the dogs 22 and 23, and of the latch 24 and projection II.

O eration of the circuit breaker it may be effected by means of a closing relay 3. having a normally open contact member 30b for effectin energization of the operating winding ll. The closing relay 3|! may be provided with an operating winding I2 disposed to be energized through means such as the push button switch 34. A cut-ofl relay ll may be provided for deenergizing the operating winding 32 of the closing relay 30 whenever the circuit breaker l2 closes. The cut-oil relay 35 may be provided with a normally closed contact member "b for completing an energizing circuit for the operating winding 32 of the closing relay, and may be provided with an operating winding II which may be energized through a normally open contact member lie on the circuit breaker operating rod I.

In order to prevent reclosure of the circuit breaker l2 for a predetermined interval of time after it has once opened, means such as the time delay relay 38 may be provided. The time delay relay may be of the type described in detail in Patent No. 1,979,709, which issued on November 6, 1934, to W. Schaelchlin et al., and comprise an armature 39 having an operating winding 40, which may be connected for energization through a normally open contact member 300 of the closing relay, and a short circuiting turn or sleeve which retards collapse of the magnetic flux produced by the operating winding, and hence delays return of the armature to the deenergized position. A neutralizing winding 42 may be provided for bucking down the residual flux produced by the operating winding to provide for reducing the effectiveness of the short circuiting sleeve and varying the time delay in the return of the relay to the inoperative position after the operating winding 40 is deenergized. The neutralizing winding 42 may be connected to a suitable source of electrical energy through an adjustable control resistor 43, through normally open contact members 38b so as to permit rapid operation of the relay to the operative position.

In operation, the push button switch 34 may be closed so as to provide an energizing circuit for the operating winding 32 of the closing relay 38, through a circuit extending from positive through contact member 34a of the push button switch 34, a control resistor 4|, operating winding 32, and contact member 35b of the cut-oi! relay to the negative terminal of the source. The closing relay 38 operates, connecting the operating winding l8 of the circuit breaker l2 to the source through contact member 38b. The operating winding 48 of the time delay relay 38 is also connected to the source through contact member 380. A holding circuit is provided for the operating winding 32 extendin rom negative through contact member 38a, operating winding 32, control resistor 44, conductor 45, and contact member 38a to the positive terminal of the source. The neutralizing winding I2 is likewise energized through contact member 8817.

As soon as the circuit breaker I2 closes, the operating winding 38 ofthe cut-off relay 35 is energized through the circuit extending from negative through contact member I211 of the circuit breaker, operating winding 36 and contact member 38a of the time delay device 38 to positive. Operation of the cut-off relay 35 interrupts the initial energizing circuit of the operating winding 32 of the closing relay 38 by opening contact member 351;, and shunts the operating winding down by closing normally open contact mem ber 35a. The operating winding l8 of the circuit breaker I2 is thereupon deenergized by the openingot contact member 38b.

Should the circuit breaker l2 be opened for any reason such as, for example, operation of the push button switch 21, the lever 20 is actuated so that the projection 25 clears the latch 24, and contact member I2b opens, interrupting the energizing circuit for the operating winding 48 of the time delay device 88. After a predetermined interval of time which depends upon the adjustment. of the control resistor 43, the time delay device 38 returns to the inoperative position. Upon the opening of contact 38a, the cut-off relay 35 is deenergized and contact member 35b closes. This permits reenergization of the operating winding 32 for effecting a reclosure of the circuit breaker after the expiration of the predetermined interval of time from the opening of the contact member I2b of the circuit breaker.

Accordingly, the circuit breaker I: may not be reclosed for a predetermined interval of time after it has once opened. Referring to Fig. 2, the reference numeral 58 may denote, generally, a control system including forward and reverse circuit breakers 52 and 53 respectively, for reversibly connecting a load device M to a source of electrical energy represented by the conductors I5.

The circuit breakers 52 and 53 may be substantially the same as the circuit breaker 12 which was described in connection with the system shown in Fig. 1, and may comprise operating windings 54 and 55 for actuating operating mechanisms 56 and 51 for actuating main contact members 58 and 59, respectively. Each of the circuit breakers may be provided with trip means including trip windings 60- and BI, which may be energized through means such as the push button switches 62 and 63, respectively.

Operation of the forward circuit breaker 52 may be effected by means of a closing relay 85 and a cut-01f relay 66, having operating windings 61 and .68, respectively. The reverse circuit breaker 53 may similarly be controlled by a closing relay I8 and a cut-off relay H, having operating windings l2 and 13, respectively.

In order to prevent reclosures of the forward and reverse circuit breakers, as well as successive closures of these two circuit breakers within predetermined intervals of time during which ionized conditions may exist at the main contacts, time delay devices 15 and 18 may be provided in connection with the circuit breakers 52 and 53, re;- spectively. The time delay devices may be similar to the time delay device 88 described in connection with the system of Fig. 1, and may comprise operating windings l1 and together with neutralizing windings 88 and 8|.

In operation, the circuit breaker 52 may be closed by operating a. push button switch 83 to complete an energizing circuit for the operating winding 61 of the closing relay 65. The operat 66, conductor 86, back contact 530 of the reverse circuit breaker 53, and back contact 180 of the time delay device 16. The closing relay 65 operates, providing an energizing circuit for the energizing winding 54 of the forward circuit breaker 52 through front contact 65b, and provides a holding circuit for the operating windin 61 through contact member 85a. At the same time, an energizing circuit is provided for the operating winding I1 of the time delay device I5 through back contact 650.

Upon operation of the circuit breaker 52, 80 energizing circuit is provided for the operating winding 68 of the cut-off relay 88,'through front contact 52a of the forward circuit breaker and front contact 15a of the time delay device 15 so that the cut-off relay operates and disconnects 05 the operating winding 61 of the closing relay from the source. At the same time, front contact 5227 closes and provides a holding circuit for the operating winding 1'! of the time delay device I5.

Operation of the circuit breaker 52 also opens 70 back contact 520 which interrupts the energizing circuit for the operating winding 12 of the closing relay 18, thereby preventing inadvertent operation of the reverse circuit breaker 53.

Upon tripping of the forward circuit breaker 52 for any reason such as, forexample, operation ing 11- of the time delay device 15 is deenergized by the opening of contact member 52b. However,

the time delay device remains in the-operative position for a predetermined interval of time. Accordingly, the operating winding 68 of the c utoif relay 56 of the forward circuit breaker is held energized through a circuit extending from positive through contact member 15a, operating winding 58, and contact member 560. Accordingly, reclosure'oi the forward circuit breaker 52 is prevented since the operating circuit for the closing relay 65 is interrupted at contact member 5617 of the cut-off relay 66 While the time delay device 15 remains in the operative position. Likewise, the operating circuit for the closing relay of the reverse circuit breaker 53 which extends from positive through push button switch 88, control resistor 89, operating winding 12, and contact member 1 lb, conductor 90-, contact member 52c, and contact member 150, is interrupted at contact member 150 so long as the time delay device remains in the operative position. Accordingly, the forward circuit breaker 52 may not be reclosed until the expiration of the interval of time, and neither may the reverse circuit breaker 53 be closed for the same interval of time,

which is measured from the time of opening of the circuit breaker 52. The time delay is similarly eifected ina reverse sequence of operations of the circuit breakers 52 and 53.

From the above description and the accompanying drawing, it will be apparent that we have provided a simple and effective control system which is equally applicable to all types of circuit interrupters, and wherein the time delay between operations is started only after the circuit interrupter has started to open and is independent of how long the interrupter has previously been closed. Immediate reclosing or the closing of a second interrupter is positively prevented until after a predetermined time interval during which,

for example, all ionized gases in the vicinity of the contacts will have escaped. Since the time delay device is operated prior to closure of the mediately upon closure or even during closure.

This guarantees continuity of the cycle of operations even under the worst operating conditions.

Since certain changes may be made in the above-described construction, and different em,- bodiments of the invention may be made without departing from the spirit and scope thereof, it isintended that all matter contained in the above description and shown in the accompanying drawing shall be considered as illustrative and not in a limiting sense.

We claim as our invention:

1. In a control system for a circuit interrupter, relay means operable to effect closure of the circuit interrupter, time delay means having main and neutralizing windings responsive to opening of the circuit interrupter operable to render the closing relay means ineffective to close the .circuit interrupter for a predetermined time after the circuit interrupter commences to open, and

circuit means connecting the neutralizing winding for energization only when the time delay means is operated.

2. A control system for a circuit breaker comcircuit breaker, time delay means having main and neutralizing windings controlled by the control means operable to render the control means inefiective to reclose the circuit breaker for a predetermined time after the circuit breaker opens and circuit means connecting the neutralizing winding for energization only when the time delay meas is operated.

3. A control system for a circuit breaker comprising, a closing relay operable to effect closure of the circuit breaker, cut-off means operable upon closure of the circuit breaker to render the closing relay inoperative, and a time delay relay operable in response to operation of the closing relay to provide a holding circuit for maintaining the cut-oil? means operated for a predetermined time after the circuit breaker is opened.

4. A control system for a circuit breaker having main contacts operated by a mechanically tripfree operating mechanism provided with an operating winding and normally open auxiliary contact means comprising, additional normally open contact means associated with the circuit breaker contact means, a closing relay operable to provide an energizing circuit to close the circuit breaker, a cut-oil relay operable to render the closing relay inoperative, time delay means operative in response to operation of the closing relay to set up an operating circuit for the cut-ofi relay, and circuit means including the normally open contact means associated with the circuit breaker trip-free mechanism providing for completing the operating circuit of the cut-off relay, said time delay means being operable to remain in the operated position to provide an energizing 4 circuit for the cut-off relay for a predetermined time after the normally open contact means of the trip-free mechanism open, whereby the closing relay is rendered inoperative for said interval.

5. A control system comprising, a first circuit breaker, means including a closing relay and a cut-off relay operable to effect closure of the first circuit breaker, a second circuit breaker, additional means including a closing relay and a cut-ofi relay operable to effect closure of the second circuit breaker, time delay means controlled by the closing relay of the second circuit breaker and operable for a predetermined time after opening of said second circuit breaker to prevent operation of the closing relay of the first circuit breaker, and additional time delay means controlled by the closing relay of the first circuit breaker and operable for a predetermined time after opening of the first circuit breaker to prevent operation of the closing relay of the second a circuit breaker.

6. A reversing control system comprising, a forward circuit breaker operable to connect a load device to a source of electric energy in one sense, a reverse circuit breaker operable to connect the load device to the source in the opposite sense, a closing relay operable to provide an operating circuit for the forward circuit breaker, a cut-oil relay operable to render the closing relay inoperative, an additional closing relay opera-hie to provide an operating circuit for the reverse circuit breaker, an additional cut-off relay operable to render the additional closing relay inoperative, time delay means operable in response to operation of the closing relay of the forward circuit breaker and operable for a predetermined time after the forward circuit breaker opens to prevent operation of the additional closing relay, additional time delay means operable in response to operation of the additional closing relay and 7 operable tor a. predetermined time after the reverse circuit breaker opens to prevent operation of the forward circuit breaker closing relay, and means responsive to closure of either oi the circuit breakers preventing operation of the closing .relay of the other circuit breaker.

CARROLL- M. WILLIAMS. BENJAMIN I. HAYFORD.

REFERENCES CITED The following references are of record in the file of this patent:

Nurnber Reagan Jan. 15, 1946 

